Windows, doors and other openings in exterior structures or walls of buildings are known to have sills or thresholds designed to seal inclement weather out and generally shed water away from the window or opening and prevent moisture ingress between structure underlayment or sheathing and the exterior siding or veneer of the building. Unfortunately, known sills that are made of wood can rot and peel paint over the years, and stone sills are expensive and difficult to install. Both wood and stone sills typically require caulking to prevent water seepage into the structure. Moreover, this caulking requires continual maintenance to reseal old chalk that has cracked or loosened.